Doing my calculations, the best I can get with stock heads is about 9.1:1. I was targeting 8.4:1 - 8.8:1. This doesn't seem possible without milling AFR Heads.

What is the best CR with stock heads? Then I suppose I would build the boost to match the best CR... right? 10#s?

 

JE makes some nice "extreme duty inverted dome" pistons. with either a -31 or a -22cc dish. They have worked very well for me. You won't be able to get to the ~8.5:1 range with stock combustion chambers. But as you suggest, with 10psi you should be ok.

Rich Krause

 

So, with stock heads, Zero Deck, and 31 cc inverted domes, I should be around 8.8:1?